ansys问题错误如何解决

After NUMMRG,ALL, node 1001 (and possibly others) is associated with
more than one solid model entity. Future commands which depend on the
node to solid model connectivity (meshing, mesh clearing, solid BC
transfer, etc.) may not operate properly.
The value of UY at node 4855 is 672334301. It is greater than the
current limit of 1000000. This generally indicates rigid body motion
as a result of an unconstrained model. Verify that your model is
properly constrained.
我做钢筋混凝土梁的受力分析出现这个问题，当荷载变小是定二个问题就没有了，为什么？